Electromechanical door operator



Oct. 5, 1965 H. w. FERGUSON ETAL 3,210,067

ELECTROMECHANICAL DOOR OPERATOR Filed Aug. 8, 1962 5 Sheets-Sheet 1 INVENTORS HAROLD W. FERGUSON FRANCIS J KALOG arm/7 WM 5 /41 ATTORNEYS Oct. 5, 1965' H. w. FERGUSON ETAL 3,210,057

ELECTROMECHANICAL DOOR OPERATOR 3 Sheets-Sheet 2 Filed Aug. 8, 1962 FIG] FIG. 6

INVENTORS HAROLD W. FERGUSON FRANCIS J. KALOG WW7; WWW/57w ATTORNEYS Oct. 5, 1965 H. w. FERGUSON ETAL 3,210,057

ELEOTROMEOHANICAL DOOR OPERATOR 3 Sheets-Sheet 3 Filed Aug. 8, 1962 EDUQU mm On @OPOE INVENTORS HAROLD W. FERGUSON FRANCIS J. KALOG United States Patent 3,210,067 ELECTROMECHANICAL DOOR OPERATOR Harold W. Ferguson and Francis J. Kalog, New Britain, Conn., assignors to The Stanley Works, New Britain,

Conn., a corporation of Connecticut Filed Aug. 8, 1962, Ser. No. 215,710 15 Claims. (Cl. 268-65) The present invention relates to electromechanical actuators of the type commonly used for effecting timely opening and closing movement of a pedestrian exit or entrance door.

It is a principal object of this invention to provide a new and improved electromechanical actuator which incorporates a novel power clutching arrangement.

It is a further object of this invention to provide an improved electromechanical actuator incorporating a power clutching arrangement in which electrical power is disconnected from the drive motor when the clutch is decoupled.

It is another object of this invention to provide an improved electromechanical actuator that is rapidly responsive and sensitive to the demands of the pedestrian traffic and yet safe against injury to pedestrians and damage to any obstruction in its path of movement.

Still another object of this invention is to provide an improved electromechanical actuator including a releasable nonslipping clutching arrangement and means for cushioning the movement of the door.

It is a further object of this invention to provide a door actuator incorporating a novel power train for opening and closing the door and a novel electrical control system for the power train that is sensitive to and which rapidly responds to the demands of the pedestrian traffic using the doorway and which ensures a foolproof system for bringing about normal cycling of the door between the open and closed positions, and which additionally delays or alters the normal door cycle in response to pedestrian tratfic or other conditions encountered in use.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the invention which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a perspective view, partly broken away, of a door installation incorporating the electromechanical operator of this invention;

FIG. 2 is a top plan view of a mechanical transmission subassembly of the electromechanical operator of FIG. 1;

FIG. 3 is a side view, partly in section, of the mechanical transmission subassembly of FIG. 2;

FIG. 4 is a schematic diagram of an electrical control system of the electromechanical operator of this invention;

FIG. 5 is a fragmentary top View of a door installation illustrating a modified form of this invention;

FIG. 6 is an enlarged fragmentary sectional view taken along line 66 of FIG. 5; and

FIG. 7 is an enlarged perspective view of a portion of the auxiliary power means of FIG. 3.

Referring to FIG. 1, the electromechanical actuator of this invention is shown as being mounted in a header above a doorway for opening and closing a door 10. As shown in FIG. 1, the mechanical actuating components of the door operator are mounted on a base plate 14 so that they may be installed and removed as a unit, and includes a reversible motor 16, which is shown as being of the alternating current capacitor type, and has its out- 3,21,957 Patented Get. 5, 1965 put shaft drivingly connected to reduction gearing 18 through a coupling 19. There is further provided a final drive assembly 20 driven by the reduction gearing 18 and having a downwardly depending output spindle 22 positioned in axial alignment with upstanding pivot shaft 26 fixed to the door 10. Spindle 22 is drivingly connected to pivot shaft 26 through a coupling 24 for opening and closing door 10. A cooling fan 28 driven by fan motor 30 is provided to cool motor 16.

Also shown as being mounted on base plate 14 is an electrical control unit 32 which houses a major portion of the components of the electrical system for controlling the operation of the motor.

In order to provide a pedestrian-responsive signal for energizing the motor 16 to operate the door 10, a conventional switch-type contact carpet 34 is provided. It is apparent that such a signal could also be provided by a conventional photoelectric sensing system or by hardware mounted for manual actuation by pedestrians using the doorway. As shown, the contact carpet 34 comprises two portionsan approach or entering carpet 36 which is adapted when Walked upon to close an approach switch 38 (FIG. 4), and a hold or safety carpet 40 over which the door is operated and which is adapted to close the hold or safety switch 42 (FIG. '4) when depressed by the weight of a pedestrian or other object.

Referring specifically to FIGS. 2 and 3, the reduction gearing 18 has an input shaft 44 which is driven by motor 16 through the coupling 19 (FIG. 1) and, in turn, drives an output crank 46 in a clockwise direction, as seen in FIG. 2, when the motor 16 is driven in the forward, or door-opening direction. The reduction gearing 18 includes a spur gear train (incompletely shown) to drivingly connect the input shaft 44 and an intermediate shaft 48 and further includes a worm 50 keyed to the shaft 48 and driving a worm gear wheel 47 which, in turn, drives the output crank 46. The reduction gearing may be chosen so as to provide any desired period of time for the opening and closing cycle of the door 10. Because an irreversible worm and worm gear wheel are included in the gear train, it will be apparent that torque can be transmitted only from the motor to the door and that the motor 16 cannot be driven by torque applied to the door 10.

The final drive assembly 20 includes rotatable inner hub 52 which is driven through a clutch, generally designated by the numeral 54, mounted on a rotatable ring member 56 which is positioned concentrically around the hub 52. A drive link 58, having its ends pivotally mounted on both crank 46 and ring 56, drives the ring 56 of clutch 54 in a clockwise direction approximately 90 during the door-operating cycle.

It will be noted in FIG. 2, that crank 46 is shorter than the radial distance between the centers of clutch spindle 22 and pivot 23 so that the angular travel of crank 46 substantially exceeds that of clutch ring 56. Moreover, the ends of drive link 58 are angularly disposed so that at the beginning and end of the opening and closing portions of the door-operating cycle, the rate of change of angular movement of clutch 54 (and door 10) is minirnized. Stated in another way, the crank 46 and the radial line through clutch spindle 22 and pivot 23 are perpendicular to drive link 58 at an intermediate position or when the door 10 is about 45 open. This arrangement reduces the torque required to overcome the inertia of the door at the beginning of the door-opening and closing operation and results in a maximum door speed when the door is about 45 open.

The clutch 54 comprises two curved clutch segments 60 and 62 positioned radially of hub 52. Each of the clutch segments are pivotally mounted on the ring 56 'by a pair of pins 64 and 66, respectively, for movement toward and away from the driven hub 52 and have, intermediate their ends, a pair of inwardly extending trapezoidalshaped dogs 70 normally closely received in mating trapezoidal-shaped recesses 72 in the hub 52.

The free ends of the clutch segments 60 and 62 are joined by a torque-limiting device which. includes a pair of toggle links 80 and 82. One end of toggle link 80 is pivotally mounted to clutch segment 60 by a pin 84. The other end of toggle link 80 is pivotally mounted by a pin 96 to yoke 92 of a torque-adjusting bolt 98. One end of the other toggle link 82 is pivotally mounted by a pin 86 to clutch segment 62 and the other end of toggle link 82 is pivotally mounted to an intermediate point on toggle link 80 by pin 90.

The adjusting bolt 98 is slidably received within an opening in a guide 100 that is pivotally mounted upon the clutch segment 60, and a compression spring 104 sur rounds bolt 98 to bear against an enlarged head portion 106 on the guide 100 and against the knurled adjusting nut 102. Accordingly, the compression spring 104 exerts an axial force against yoke 92 which is amplified by toggle links 80 and 82 to urge the clutch segments 60 and 62 inwardly toward the hub 52 thereby to maintain the dogs 70 within the recesses 72. It will be apparent that by the use of this force-amplifying toggle arrangement, the size of spring 104 can be greatly reduced.

The faces 107 of the dogs 70 and the mating recess wall 108 lie in planes inclined approximately 15 to the radius of hub 52 and are in contact when the clutch 54 is fully engaged. As the dogs or lugs 70 have their inclined faces 107 facing in opposite angular directions, it can be seen that the clutch 54 is bi-directional and that torque is primarily transmitted through clutch segment 60 and its dog 70 to the hub 52 when the clutch is moving in the clock wise or door-opening direction and through clutch segment 62 and its dog 70 in the door-closing direction.

It will be observed that the faces 74 of the dogs 70 and the mating faces 76 of the recesses 72 are disposed at an angle of approximately 60 relative to the radius of hub 52 which. is substantially greater than the corresponding angle of faces 107 and 108 of the dogs 70 and recesses 72 for purposes hereinafter explained.

The breakaway torque of the clutch 54 can be adjusted by adjusting the knurled nut 102 which is threaded on bolt 98 to change the spring force of compression spring 104. When the torque transmitted through the clutch in, say, a clockwise direction is higher than a preselected amount, the dog 70 of clutch segment 60, through which the torque is then being transmitted, begins to slide outwardly on wall 108 of the recess to move its associated clutch segment 60 outwardly against the compressive force of spring 104 acting through toggle links 80 and 82. At the same time, the dog 70 of clutch segment 62 will be cammed outwardly by the recess wall 76 of its mating recess. Since these faces 74, '76 have a greater angle relative to the radius of the hub 52 than the corresponding angle of the faces 107, 108, it will be apparent that the dog 70 of clutch 60 (through which the torque is being principally transmitted) will become disengaged slightly 'before the dog 70 of clutch 62 due to the greater are subtended by faces 74, 76. This facilitates the reengagement of the clutch segments 60, 62 and hub 52 and reduces the stresses on the clutch. Moreover, as shown in FIG. 2, the outer ends of dogs 70 are spaced from the bottoms of recesses 72 by a small clearance. This will insure that the mating, angularly disposed faces of dogs 70 and recesses 72 are normally in positive contact so that their relative angular relationsip during engagement is fixed. This arrangement also eliminates any backlash in the clutch.

From the foregoing, it will be apparent that by the selection of the angle of the faces 107 and 108 of the dogs 70 and their mating recesses, the breakaway torque of the clutch 54 may be easily selected. Moreover, it will be apparent that upon any sudden reversal or starting of the motor 16 the clutch arrangement described above will soften the shock loading due to slight relative angular movement of the clutch segments 60 and 62 and hub 52 as a result of the camming action of the mating faces of the dogs 70 and the recesses 72. Such functioning, of course, does not normally result in the decoupling of the clutch. In addition, the proper selection of the angularity of the faces 107 and 108 in conjunction with a force amplification provided by the toggle links 80, 82 results in a clutching arrangement in which the compression spring holding the clutch members in engagement is unusually small in relation to the forces transmitted. Finally, in the event of a power failure, the electromechanical actuator of this invention provides an emergency release which will permit the door to be opened by the application of a force on the door which exceeds the breakaway torque of the clutch. When so opening, the door will remain in an open position until manually reset by swinging the door to the position in which the dogs 70 of the clutch 54 are reengaged in their respective recesses of the hub 52.

As previously stated, the spindle 22 is directly coupled to hub 52 of the clutch and is further rotatably mounted in a pair of bearings 53 as best shown in FIG. 3.

In order to minimize the loading imposed on the driving gears and clutch mechanism under conditions of initiating the movement of the door under full motor torque, and in order to damp the movement of the door at the end of its opening or closing cycle, an auxiliary power mechanism is provided. Referring to FIGS. 3 and 7, the auxiliary power mechanism comprises a pair of interfitting cam washers 110 and 112 and a coil spring 113 which is positioned around shaft 22 between a shoulder on the shaft 22 and the upper washer 110. The upper washer 110 is locked against rotative movement by a locking pin 115 which slidably engages a slot in its edge. Lower washer 112 is mounted to rotate with shaft 22. The mating surfaces of washers 110 and 112 are provided, respectively, with a pair of diametrically disposed V-shaped recesses 114 and a pair of complementary V-shaped lugs 116.

With the door in the closed position, the peaks of the lugs 116 are preferably positioned on the tapered surface of the recesses 114 against which it is urged by compression spring 113, although the arc subtended by the recesses 114 may be such that the lugs 116 rest on the nontapered portion of the lower surface of washer 110. With either construction, as the door opens, the compression spring 113 will aid the motor in overcoming the inertia of the door since it will bias the lugs 116 toward the bottom of the recesses 114 of the washer 110. When the door is 45 opened, the peaks of the lugs 116 will have moved to the bottom of the recesses 114. As the door continues to move toward an open position, energy will be stored in the compression spring 113 as it is compressed due to the camming action of the tapered wall of the recesses 114 which urges the washer 110 upwardly. This increases the loading on the motor tending to cause it to slow down and thereby cause the door speed to be reduced as it approaches its fully opened position.

In addition to the functioning of the auxiliary power means in overcoming the inertia of the door as it opens and closes, it will be apparent that this mechanism will minimize the backlash in the gearing by providing a positive load on the gearing in both its opened and closed positions due to design and angular positioning of the:

washers 110 and 112. If the lugs 116 rest on the non--" tapered surface of washer 110, the backlash will be minimized due to the loading imposed by the friction forces acting between washers 110 and 112.

FIG. 4 illustrates an electrical control system .for controlling the electromechanical actuator. The electrical system includes a master switch 120 for connecting the system to an electrical power source which, in the specific embodiment shown, is a conventional alternating current 110-120 volt source. Generally, the electrical control system includes three circuits: a motor power circuit designated 122 connected directly to the AC. source through the master switch 120; a signal and safety circuit designated 124 connected to the AC. source through the master switch 120 and a step-down transformer 126 preferably having 24 volts output; and a motor control circuit designated 128 connected to the secondary or output of the transformer 126 through a rectifier bridge 130 preferably having 24-volt DC. power output.

In FIG. 4 the switches and relay contacts are illustrated as being either open or closed to correspond with their condition when the master switch 120 is closed and neither approach switch 38 nor safety switch 42 is actuated.

Four normally closed door-cycle switches 132, 134, 136 and 138 in the motor control circuit 128 are mounted for selective operation by a pair of cams 140 and 142 fixed to the output crank 46 for rotation therewith (see FIG. 2). The switches 132 and 134 are supported by a plate 150 that is adjustably mounted for angular movement about the axis of rotation of the output crank 46 by the screws 152. The switches 136 and 138 are similarly supported upon a plate 154 that is adjustably mounted by the screws 156. The plates 150 and 154 and, therefore, the position of the normally closed door-cycle switches 132, 134, 136 and 138 relative to the cams 140 and 142 is selected so that the switch 134 is open when the door is closed, but closes just after the door begins to open and remains closed until the door returns to its fully closed position; the switch 136 is closed when the door is closed and is opened when the door has rotated 90 or to its fully open position; the switch 138 is open when the door is closed and is closed when the door is open approximately 75 or more; and the switch 132 is open when the door is closed and is momentarily closed as the door passes through the approximately 25 open position.

Upon closing the master switch 120, the fan motor 30 is energized for continuously driving the fan 28, and power is applied to the terminals of the carpet-operated approach switch 38 and safety switch 42 so that they are ready to energize cycle-initiating relay A and safety relay B, respectively. The door-opening relay C, the motor forward-control relay D, the motor reverse-control relay E and the motor low-speed relay F in the motor control circuit 128 remain deenergized while the door is fully closed and are selectively energized as hereinafter more fully described for controlling the opening and closing of the door.

The normal opening and closing cycle of the door is initiated upon the closing of the approach switch 38 by a pedestrian walking on the entering carpet 36. Approach switch 38 then energizes the cycle-initiating relay A which closes the contact A1 to complete the circuit to the door-opening relay C and to the time delay circuit therefor comprising the capacitor 160 and the resistor 162. The door-opening relay C, in turn, closes the contact C-2 to energize the forward control relay D and opens the contact C-4 to insure that the circuit to the reverse-control relay E remains open during the dooropening cycle. Further, the door-opening relay C closes the contact C1 in the signal and safety circuit and opens the contact C-3 to insure the circuit to the safety relay B remains open, thereby preventing the subsequent closing of the safety or holding switch 42 by a pedestrian passing through the door from energizing the safety relay B to terminate the opening movement of the door. Under such normal operating conditions the closing of safety or holding switch 42 will continue to energize cycle-initiating relay A through switch B-l to keep the door open.

As a result of the energization of forward-control relay D, the contact D-1 of the motor power circuit 122 is also closed to apply full line voltage to the motor fields 33 and 33a to turn the motor in the forward direction for opening the door. The energization of forward-control relay D also closes the contact D-2 of the motor power circuit 122 to connect the resistor 164 and contact F-l which is subsequently closed to obtain reduced-speed operation of the motor. Further, energization of the for- 6 ward-control relay D opens the contact D4 of the motor control circuit 128 to disconnect the time delay circuit comprising the capacitor 166 and resistor 168 from the low-speed relay F and closes the contact D-3 to connect the low-speed relay F to the switch 138.

After the motor 16 rotates to turn crank 46 clockwise (FIG. 2), the normally closed switch 134 closes as it is disengaged by cam 140 so that the reverse-control relay E can be energized by the subsequent closing of contact 04.

After the door has opened about 75, the normally closed switch 138 is closed as it is disengaged by the cam 142 fixed to the output crank 46 to complete the circuit to the low-speed relay F. Low-speed relay F, in turn, closes the contact F-l in the motor power circuit 122 to place the resistor 164 in parallel with motor field 33a through the contact D-2 which was previously closed by the forward-control relay D, thereby to effect a reduced torque output from the motor 16 and slow or dampen the opening movement of the door. Contact F-2 of the damping circuit for capacitor 166 is also opened so that the damping circuit cannot be effective at this time.

When the door reaches the or full open position, the normally closed switch 136 is opened by the cam fixed to the output crank 46 to open the circuit to the forward-control relay D, thereby returning thecontacts D-1, D-2, D3 and D-4 to the positions shown in FIG. 4. This removes the electrical power from the motor field windings 33 and 33a to terminate the opening movement of the door which will remain stationary in view of the worm drive gears of gearing 18. The circuit to the low-speed relay F is also opened and the time delay circuit comprising the capacitor 166 and resistor 168 is reconnected across low-speed relay F. As the capacitor 166 of the time delay circuit for the low-speed relay F was not previously energized, it does not cause a delay in the deenergization of low-speed relay F so that the contact F-1 in the motor power circuit immediately opens and the contact F2 of the damping circuit for capacitor 166 is immediately closed through the resistor 169.

The door remains open as long as either the approach switch 38 or safety or hold switch 42 remain closed to retain cycle-initiating relay A and door-opening relay C energized and, therefore, as long as a pedestrian is standing on the contact carpet 34. When both the safety and approach switches 42 and 38 become opened, the cycle-initiating relay A is deenergized, thereby opening the contact A-1 to break the circuit to the door-opening relay C. However, after contact A1 opens, the relay C remains energized for a short interval of time due to the time delay circuit comprising the capacitor and resistor 162 which discharges through door-opening relay C to maintain the contact C-4 of the motor control circuit 128 open so that the door will dwell at the full open position.

As the capacitor 160 becomes discharged, the dooropening relay C is deenergized, the contact C-4 is closed to complete the circuit to the reverse-control relay E which, in turn, closes the contacts E1 to apply full line voltage to the motor fields 33 and 33a in the reverse direction for reverse rotation and closes E-2 to connect resistor 162 and contact F1 which are subsequently used in the reduced-speed operation of the motor. The door then moves toward its closed position with initial closing movement of the door being accompanied by immediate closing of the switch 136 by cam 142 so as to prepare the forward relay D for energization by the contact C-2.

The switch 138 is opened by cam 142 after 15 of closing travel of the door thereby preparing the circuit to the low-speed relay F for energization by contact D-3, and the switch 132 is momentarily closed after 65 of closing travel of the door to momentarily complete the circuit to the low-speed relay F through the contact D-4 and to energize its time delay circuit comprising the capacitor 166 and resistor 168. The energization of the relay F closes the contact F-i in the motor power circuit 122 to place resistor 164 in parallel with the motor field 33 to thereby reduce the torque of the door as it approaches its closed position. The time delay circuit for the relay F insures that relay F will continue to be energized for the normal closing period of the door and until the door reaches the fully closed position whereupon the switch 134 is opened to deenergize the reverse-control relay E and thereby open the contacts E-li and 15-2 and disconnect the power to the motor. As soon as the relay F is deenergized upon dissipation of the charge on the capacitor 166, the contact F2 will close to completely discharge capacitor 166 through the resistor 169 and the door-closing cycle is completed.

If the normal delay period provided by the time delay circuit for the relay F terminates prior to the door reaching its fully closed position as, for example, due to a retardation of the door by wind, the low-speed relay F will be deenergized to open the contact F-l so that full voltage is applied to motor fields 33 and 33a and full torque will be applied to close the door.

If at any point during the closing movement of the door, the approach switch 38 is actuated, the cycleinitiating relay A will be energized to close the circuit to the door-opening relay C thereby opening the circuit to the reverse-control relay E by opening the contact C-4. This will immediately terminate the reverse operation of the motor and the forward operation thereof will be accomplished according to the previously described cycle.

In the event that a pedestrian steps on the safety carpet 40 to close the switch 42 as the door is closing, the circuit to the safety relay B is completed thereby opening the switch Bl to prevent energizing the cycle-initiating relay A. Consequently, if the door is in its closing cycle, it will continue to close. If, however, a pedestrian steps onto the safety carpet 40 during the opening movement of the door, the safety switch 42, as has been explained, will not affect the continuing opening movement of the door.

A modification of this invention is shown in FIG. wherein the electromechanical actuator is mounted externally of the header of the door and the door is driven through a linkage arrangement including a pair of links 180 and 182 connected, respectively, to the drive spindle 22 of the actuator and to a safety arm 184. The safety arm 184, though pivoted at one end upon a support 186 fixed to the door, is normally retained for movement with the door by a releasable latch 188, an enlarged view of which is shown in FIG. 6. The releasable latch 188 includes a hardened detent 1% having a hemispherical end snugly received within a recess 192 in the safety arm 184 so as to retain the arm 184 against movement relative to the door during the normal inwardly swinging operation of the door (i.e., counterclockwise as viewed in FIG. 5). However, if power'to the actuator should be interrupted or if under emergency conditions it is desired to swing the door clockwise as viewed in FIG. 5, the detent 190 will disengage from the recess 192 of safety arm 184 against the bias of spring 194 so as to disconnect the door from the safety arm 184i, thereby terminating the driving connection between the door and the safety arm 18a. The door can be reconnected to the safety arm by manually swinging the door so that the detent 190 is latched in the recess 192.

It can be seen, therefore, that the door control system of this invention provides a number of features which not only assure that the door is quickly and positively opened and closed and is brought to its fully opened and closed positions smoothly and at a decelerated rate, but additionally reduces the likelihood that the door will injure a pedestrian or become damaged by an obstruction in its path. Additionally, the novel electrical and mechanical arrangement of parts insures safe, reliable and foolproof operation without resetting throughout a long-operating period.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

We claim:

1. An electromechanical door actuator comprising a reversible motor, a gear train including a Worm and worm gear wheel operatively connected to the output shaft of the motor, a crank rotatably driven by said gear train, a clutch driven by said crank and having an output shaft and a hub, means for connecting the output shaft to a door to be opened and closed, a pair of pivotally mounted clutch segments surrounding said hub, each of said clutch segments having a dog for engaging a recess on said hub and yieldingly and positively positioning said clutch segments with respect to said hub, means comprising a compression spring and a. toggle mechanism connected to the free ends of said clutch segments whereby the toggle mechanism amplifies the compressive force of said spring in urging said segments toward said hub, and auxiliary mechanical and electrical means for modifying the relationship of the torque of said actuator to the load imposed on said actuator at the beginning and at the end of the opening and closing portions of the door-operating cycle.

2. An electromechanical door actuator comprising a reversible motor, a gear train operatively connected to the output shaft of the motor, a crank rotatably driven by said gear train, a clutch driven by said crank and having an output shaft and a hub, means for connecting the output shaft of the clutch to a door to be opened and closed, said clutch comprising a pair of pivotally mounted clutch segments surrounding said hub, each of the clutch segments having a dog for engaging a recess of said hub and positively positioning said clutch segments with respect to said hub, means for biasing said segments toward said hub for yieldingly retaining said dogs in said recesses, and means for minimizing the torque imposed on said motor by said door at the beginning of the opening and closing portions of the door-opening cycle.

3. An electromechanical door actuator comprising a reversible motor, a gear train operatively connected to the output shaft of the motor, a crank rotatably driven by said gear train, a clutch driven by said crank and having an output shaft and a hub, means for connecting the output shaft of the clutch to a door to be opened and closed, said clutch comprising a pair of pivotally mounted clutch segments surrounding said hub, each of the clutch segments having a dog for engaging a recess of said hub and positively positioning said clutch segments with respect to said hub, means for biasing said segments toward said hub for yieldingly retaining said dogs in said recesses, and a pair of mating cams biased toward each other for minimizing the torque imposed on said motor by said door at the beginning of the opening and closing portions of the door-opening cycle.

4. An electromechanical door actuator comprising a reversible motor, a gear train operatively connected to the output shaft of the motor, a crank rotatably driven by said gear train, a clutch connected by a drive link to said crank and means for connecting the output shaft of the clutch to a door to be opened and closed, said clutch comprising a pair of pivotally mounted clutch segments surrounding a hub, each of the clutch segments having a dog for engaging a recess of said hub and positively positioning said clutch segments with respect to said hub, means for biasing said segments toward said hub for yieldingly retaining said dogs in said recesses, the crank driven by the gear train being shorter than the radial distance between the centers of the clutch spindle and the pivot for the drive link on said clutch, and the crank being angularly disposed at the beginning of the door-opening portion of the door-operating cycle so as to minimize the axial movement of the drive link.

5. An electromechanical door actuator comprising a reversible motor, a gear train operatively connected to the output shaft of the motor, a crank rotatably driven by said gear train, a clutch connected by a drive link to said crank, and means for connecting the output shaft of the clutch to a door to be opened and closed, said clutch comprising a pair of pivotally mounted clutch segments surrounding a hub, each of the clutch segments having a dog for engaging a recess of said hub and positively positioning said clutch segments with respect to said hub, means for biasing said segments toward said hub for yieldingly retaining said dogs in said recesses, the axis of the crank and a line through the centers of the clutch spindle and the pivot for the drive link on the clutch being perpendicular to the drive link when the door is intermediate its open and closed positions.

6. An actuator as set forth in claim wherein the axis of the crank and the line through the centers of the clutch spindle and the pivot for the drive link on the clutch are perpendicular to the drive link when the door is about 45 open.

7. An electromechanical actuator comprising a drive motor, a gear train operatively driven by said motor, a clutch drivingly connected to the output of said gear train and having an output shaft, said clutch comprising a pair of pivotally mounted clutch segments surrounding a hub, each of said clutch segments having a dog for engaging a recess on said hub for yieldingly and positively positioning said clutch segments with respect to said hub, and means for urging said dogs into engagement with said recesses, said means comprising a spring member and a toggle mechanism connected thereto and to the free ends of said pair of clutch segments whereby the toggle mechanism amplifies the spring force applied by said spring in urging said dogs into said recesses.

8. An actuator as set forth in claim 7 wherein each dog and recess is provided with a pair of mating faces disposed at different angles with respect to a line through the center of the hub with the similar angularly disposed faces facing in opposite angular directions so that torque is transmitted primarily through one of the dogs and its associated recess for one direction of rotation and through the other dog and its associated recess in the opposite direction of rotation.

9. A device as set forth in claim 8 in which the pair of mating faces of each dog and recess subtend different arcs so as to facilitate the re-engagement of the clutch after the decoupling thereof.

10. A device as set forth in claim 7 including means for modifying the relationship of the torque of the actuator to the load imposed thereon at the beginning and the end of the opening and closing portions of each cycle thereof.

11. An automatic electromechanical actuator including a drive motor for opening and closing a door, an output shaft connecting the motor to the door to be opened and closed, and auxiliary power means connected to said shaft assisting the motor at the beginning of both the opening and closing movements of the door-operating cycles and providing increased loading on the drive motor at the ends of the opening and closing portions of such cycles, said auxiliary power means further providing a force urging the door to a partially opened position when the door is in its closed position to precisely position the door and to eliminate the effects of backlash in the actuator.

12. A device as set forth in claim 11 wherein the auxiliary power means comprises a pair of cam surfaces which are resiliently urged into engagement with each other at all times and provide a force tending to move the door except when the door is in a partially open position.

13. An automatic electromechanical actuator including a drive motor for opening and closing a door, means including an output shaft drivingly connecting the motor to the door to be opened and closed, auxiliary power means connected to said shaft assisting the motor at the beginning of the door-opening and door-closing portions of the door-operating cycle and increasing the loading on the motor at the end of the door-opening and door-closing portions of said cycle, said auxiliary power means further providing a force urging the door to a partially opened position when the door is in its closed position to precisely position the door and to eliminate the effects of backlash in the actuator.

14. An automatic electromechanical actuator comprising a drive motor for opening and closing a door, means including an output shaft connecting the motor to the door, and control circuit means for the drive motor connected to control the delivery of electric power to the motor including means reducing the torque of the drive motor at the end of the door-closing movement of the door-operating cycle, said control circuit means including a time delay circuit reconnecting the motor to full electric power in the event the normal concluding movement of the closing portion of the door-operating cycle exceeds a predetermined period of time.

15. An automatic electromechanical actuator including a drive motor for opening and closing a door, means including an output shaft and reduction gearing drivingly connecting the motor to the door to be opened and closed, auxiliary power means connected to said shaft assisting the motor at the beginning of the door-opening and doorclosing portions of the door-operating cycle and increasing the loading on the motor at the end of the door-opening and door-closing portions of said cycle, said auxiliary power means further providing a force urging the door to a partially opened position when the door is in either its open or closed positions to eliminate the effects of back lash in the actuator at the opened and closed positions of the door.

References Cited by the Examiner UNITED STATES PATENTS 2,924,449 2/60 Leimer et al. 268 3,039,764 6/62 Heinsman et al. 26833 HARRISON R. MOSELEY, Primary Examiner. 

2. AN ELECTROMECHANICAL DOOR ACTUATOR COMPRISING A REVERSIBLE MOTOR, A GEAR TRAIN OPERATIVELY CONNECTED TO THE OUTPUT SHAFT OF THE MOTOR, A CRANK ROTATABLY DRIVEN BY SAID GEAR TRAIN, A CLUTCH DRIVEN BY SAID CRANK AND HAVING AN OUTPUT SHAFT AND A HUB, MEANS FOR CONNECTING THE OUTPUT SHAFT OF THE CLUTCH TO A DOOR TO BE OPENED AND CLOSED, SAID CLUTCH COMPRISING A PAIR OF PIVOTALLY MOUNTED CLUTCH SEGMENTS SURROUNDING SAID HUB, EACH OF THE CLUTCH SEGMENTS HAVING A DOG FOR ENGAGING A RECESS OF SAID HUB AND POSITIVELY POSITIONING SAID CLUTCH SEGMENTS WITH RESPECT TO SAID HUB, MEANS FOR BIASING SAID SEGMENTS 